The invention relates to improvements in methods and apparatus for the high temperature treatment of fine grained particular metal ore concentrate to obtain molten ore treatment temperatures.
More particularly, the invention relates to improvements in methods and constructions of a melting cyclone which is provided with burners for melting nonferrous metal ore concentrates and is provided with means for introducing the particulate nonferrous metal ore particles into the cyclone wherein the melt is separated from the exhaust gases under the influence of the cyclone.
For pyrometallurgical treatment of fine grained sulfidic ore concentrates in a melting cyclone, it is known such as in DE-AS 20 10 872 and German Published Application 33 35 859 to pneumatically convey fine grained solids to the cyclone in pipe conduits. The solids are introduced as a suspension with conveying air into the melting cyclone at high speeds through nozzles tangentially arranged in the jacket of the cyclone. The ore concentrate is continuously cycloned and melted in the eddy currents of the melting cyclone at high temperatures. As a consequence of the intense mass transfer between the gas and solids, high volatilization rates of the volatile solid constituents and the high melting rates of the nonvolatile constituents can be achieved in the cyclone. This known suspension melting in a cyclone has achieved special significance for the pyrometallurgical direct production of materials such as, for example, copper from sulfidic copper ore concentrates as well as from complex concentrates, yielding a comparatively pure crude copper and a low copper slag.
When the suspension of solids and conveying gas is introduced into the melting cyclone at high speeds (above 35/m/sec), the situation exists that the introduction nozzles for the fine grained solids will prematurely wear. Also, the solids particle will be pneumatically hurled into the melting cyclone with an appropriate pulse and will cause noticeable wear at the impact location against the fireproof lining of the inside cyclone wall. This is particularly true when the solids particles do not proceed to melt as they are blown into the cyclone and as a result, the inner surface of the melting cyclone will deteriorate so that shut down and repair must occur. With a melting cyclone in which fine grained solid materials are injected at high speed, the reaction time required for the reaction and melting of the particles is very short. As a practical matter, only the flight path of the particles from the injection nozzles to the inside cyclone wall is available for this reaction time and this can become too short so that exothermic calcining reaction collapses.
The risk is also present, as may be seen from German Patent 29 22 189, that the fine grained solids are introduced into the melting cyclone without conveying gas and without a vertical pulse from above and only on the basis of force of gravity. The particles are seized but not completely seized in the melting cyclone by the eddy currents and the oxygenous gas which is tangentially injected at high speed, and this results in the particles being partly hurled unreacted against the inside wall of the cyclone.
In known methods for pyrometallurgical treatment of fine grained sulfidic ore concentrates, such as sulfidic ore concentrates, for example, in a melting cyclone, the combustion of sulfide sulfur and potentially of other oxidizable constituents contained in the charged material in the oxygen atmosphere, usually supplies adequate heat in order to allow the calcining and melting process to proceed autogenously. With this situation, separate burners for the injection of fuels are not required in known melting cyclones.
An object of the invention is to provide a means for the high temperature treatment of pyrometallurgical fine grained ore concentration, particularly oxidic ore concentrates, where the melting process does occur autogenously in a melting cyclone but requires the employment of separate burners with fuel injection.
A further object of the invention is to provide for an improved method and apparatus for the temperature treatment of particulate metal ore concentration in a cyclone melting device which provides improvements over arrangements heretofore available.
A further object of the invention is to provide an improved method and structure for high temperature treating of particulate metal ore concentrates in a melting cyclone wherein the particulate material can react as completely as possible at high melting rates with the lowest possible melting cyclone wear.
A further object of the invention is to provide an improved method and apparatus for the high temperature treatment of particulate metal ore concentrates in a melting cyclone wherein losses of the gas dust and reduced specific energy consumption are achieved.